Independent rotation rock drill



Feb. 13, 1968 Filed Aug. 12, 1965 E. B. LEAR INDEPENDENT ROTATION ROCKDRILL 5 Sheets-Sheet 1 FIGJ.

FAFZ B. 45.4,?

INVENTOR.

Feb. 13, 1968 E. B. LEAR INDEPENDENT ROTATION ROCK DRILL S SheetS-Sheet2 Filed Aug. 12, 1965 INVENTOR. 54x4 5. 4542 4 N RA/E Feb. 13, 1968 Y E.B. LEAR 3,368,634

INDEPENDENT ROTATION ROCK DRILL Filed Aug. 12, 1965 v 5 Sheets-Shet 3VENTOR. 54k; 3 14k BY (K \I IQ)? {pr 1477? V United States Patent3,368,634 INDEPENDENT ROTATION ROCK DRILL Earl B. Lear, Utica, N.Y.,assignor to Chicago Pneumatic Tool Company, New York, N.Y., acorporation of New Jersey Filed Aug. 12, 1965, Ser. No. 479,113 9Claims. (Cl. 173-105) ABSTRACT OF THE DISCLOSURE Briefly, the inventioncomprises a pneumatic rock drill of the drifter type including anindependent rotation pneumatic motor unit arranged externally of thehousing and having its longitudinal axis parallel to that of the rockdrillv The housing of the motor unit is mounted upon the rock drillhousing by means of axially slidable connections at each end of themotor unit housing. The slide connection at one end includes buflerelements which yieldably resist axial movement of the motor unit ineither direction relative to the rock drill. A speed governor in themotor unit controls speed of the motor unit in a positive direction, butnot in a reverse direction.

In conventional rock drills, the drill steel is both rotated and poundedby means of the reciprocating action of a piston hammer acting throughconventional ratchettype rotation mechanism. This arrangement has itsfaults in that the rotation mechanism imposes a drag upon thereciprocating action of the piston, and provides only intermittentrotation of the drill steel. Further, at times it is desired,particularly in drifter drilling operations, to increase the rotationalspeed of the drill steel while holding the reciprocating speed of thepiston hammer steady. But this cannot be done in conventional drillswhere the rotational speed of the drill steel is dependent upon thereciprocating speed of the piston hammer.

Accordingly, an object of this invention is to provide in a pneumaticrock drill independent rotation means for controlling rotation of thedrill steel independently of the reciprocating action of the pistonhammer; and to associate this independent rotation means with the rockdrill in a practical and simple manner.

Another object of this invention is to associate with a rock drill anindependent rotation motor unit externally of the rock drill in suchmanner that the one may be readily detached from the other; so that themotor unit does not interfere with the operating efliciency of the rockdrill; and so that shocks imparted by the rock drill to the motor unitare absorbed without possibility of damage to either the rock drill orthe motor unit.

A more particular object of the invention is to provide a cushionedslidable mounting of an independent rotation motor unit with a rockdrill.

In the accompanying drawings:

FIG. 1 is a view of an independent rotation rock drill embodying theinvention, wherein the rock drill is shown in longitudinal section andthe independent rotation motor unit is shown in full;

FIG. 2 is a longitudinal section of the independent rotation motor unit;

FIG. 3 is a detail of the gear train at the forward end of theindependent rotation motor unit;

FIG. 4 is a detail section taken on line 4-4 of FIG. 2 directed to themounting at the rear end of the independent rotation motor unit; and

FIG. 5 is a section taken on line 5-5 of FIG. 2.

Reference is now directed to the drawings wherein the independentrotation rock drill illustrating the invention is disclosed. It includesa rock drill to the outside of which is detachably mounted anindependent rotation motor unit 11.

3,368,634 Patented Feb. 13, 1968 ice The rock drill shown is of thedrifter type. It includes an elongated housing generally designated 12,comprising a plurality of sections rigidly bolted together i1 end-to-endrelation, and adapted along its underside for mounting in conventionalmanner to a guide shell (not shown).

An inlet passage 13 at the rear of the housing is connectable through asuitable operator controlled supply valve (not shown) to a source ofpressure air. A conventional air distributing slide or air-blown valve14 arranged in the rear of the housing in communication with the inletpassage functions in well known manner to distribute operating airalternately to opposite ends of a piston chamber 15 of the housing torepeatedly reciprocate a hammer or piston 16 to pound a striking bar 17.This action of the valve continues automatically until the operatorshuts oil the air supply.

Supported in bearings 18 and 19' for rotation in a front head section 20of the housing is a chuck diver 21. The latter drivingly engages arotatable tool holder or chuck 22. The striking bar 17 has limited axialmovement in the chuck and chuck driver. It has an anvil portion 23projecting through the chuck driver into the piston chamber where it issubject to the pounding action of the piston. An externally projectingportion 24 of the striking bar is adapted to be coupled to a drill steel(not shown). An intermediate portion of the striking bar, defined byradially extending ears or splines 25, has a slidable splined engagementwith the chuck whereky rotation of the chuck is imparted to the strikingbar. A conventional cap 26 screwed over the front head of the housingbears against the chuck; and it may be removed when required to permitreplacement of the chuck and striking bar. A bushing 30 is provided inwhich the chuck rotates.

Reciprocation of the piston serves only to pound the striking bar. Here,it does not impart rotation to the chuck driver, nor to the chuck or thestriking bar. The motor unit 11 is operable independently of thereciprocating action of the piston and independently of the op erationof the rock drill to effect rotation of the striking bar. So as todrivably associate the Strikirg. bar with the motor unit, the chuckdriver 21 is formed with a pinion 27 which projects into a radialenargement 28 of the front head section of the housing. An idler gear 29supported in the enlargement connects pinion 27 with the pinion 31 of adriving shaft 32. A bearing 33 supporting one end of shaft 32 is mountedin the enlargement; and a second bearing 34 supporting an opposite endarea of the shaft is mounted in a cylindrical extension or support 35.The extension 35 is bolted fast to the enlargement by means of aplurality of bolts 40, and extends from the enlargement with its axis inparallel relation to the longitudinal axis of the rock drill. Thefunction of the support 35, as will be later described, is to slidablysupport one end of the motor unit 11. The driving shaft has a straightsplined end portion 36 projecting axially beyond the extension 35. Asuitable motor 37 incorporated in the housing 38 of the motor unitfunctions to transmit rotary motion through a stage 39 of reductiongearing to the driving shaft 32 and as a consequence to the striking bar17 The housing 38 of the motor unit is defined by a succession ofsections bolted together in end-to-end relation. It includes a centralsection 41 in which the motor 37 is housed. Here, the motor used is aconventional air driven motor of the radially slidable blade type. Thestage,- of reduction gearing 39 is housed in the central section(forwardly of the motor. It includes a rotatable spindle cage 42 havingoppositely extending hollow shafts 43 and 44 respectively supported inbearings 45 and 46. Bearing 45 is mounted in a back wall 47 of a closuresection 48 of the housing. The closure section is rigidly bolted to thefront end of the central housing section 41. Bearing 46 is mounted in astationary spacer 49 positioned adjacent an end plate 51 of the motor.The motor has a forward driving shaft 52 which extends freely throughthe rear hollow spindle shaft 44 into the spindle cage. This motor shaft52 has a straight splined driving connection with planetary gears 53mounted in the spindle cage. The planetary gears in turn mesh with astationary internal gear 54. The forwardly extending hollow spindleshaft 43 extends through its supporting bearing 45 and beyond theclosure wall 47 into a recess 55 defined by a forwardly extendingcylindrical skirt or sleeve 56 of the closure. In this recess thespindle shaft 43 sleeves over and has a. straight splined slidabledriving connection with the driving pinion shaft 32. The latter shaft isnot fully received into the spindle shaft, as indicated by the clearance57 at its rear. This clearance permits a desired limited axial movementof the spindle shaft 43 relative to the driving pinion shaft 32 whenrequired, as when the motor unit is jarred or shocked by the operationof the rock drill.

In this type of drilling apparatus, it is desired that the operatingspeed of the motor in a positive direction be automatically controlled.Here, a governor 58 is provided for this purpose. It is mounted in agovernor housing section 59 bolted to the rear of the central section ofthe housing. The governor section is provided with a pair of inletpassages 61 and 62 each connectable by a separate hose to a commonsupply control valve 69. When the control lever 50 of the latter ispositioned for positive operation of the motor, operating air flowsthrough the inlet 61 to a chamber 63. From the latter, it enters astationary valve cage 64 and passes through normally open radial ports65 of the cage and a connected passage 66 to the motor chamber to rotatethe rotor 67 in a positive direction. A valve 68 slida'ble in the valvecage is normally biased by a spring 69 to open condition relative to theradial ports 65. A rear driving shaft 71 of the motor has a drivingsplined connection with the body 72 of the governor. Operation of themotor rotates the governor body 72. As the motor speed exceeds apredetermined limit, flyweights 73 pivoted in the governor body swingcentrifugally to force a pin 74 to push a pin 75 against the slidevalve. This causes the latter to progressively close over the radialports 65 against the resistance of spring 69 so as to cut off operatingair from the motor and thus retard the speed of the latter.

When the control valve lever 50 is positioned for reverse operation ofthe motor, operating air enters the inlet 62 and flows into a port 76connected directly to the reverse side of the motor chamber.Accordingly, the speed of the motor in a reverse direction is notcontrolled by the governor.

The control valve 60, whereby the operator controls the supply Oifoperating air to the motor unit, is separate and independent of that(not shown) whereby the operator controls the supply of operating air tothe rock drill. This enables the operator to control rotation of thestriking bar 17 independently of the operation of the rock drill, and atspeeds which are not dependent upon the reciprocating action of the rockdrill piston.

An important feature of the illustrated independent rotation rock drillis the manner in which the motor unit 11 is mounted to the rock drillwhereby the motor unit and its mounting :are protected against damagefrom shock imparted to the motor unit during operation of the rockdrill.

The motor unit 11 is supported to the rock drill housing at its frontend upon the extension 35 of the enlargement 28; and at its rear end itis supported by means of a bracket 77. It is supported by the extensionand the bracket in such manner that its housing is clear of the housingof the rock drill, as indicated by the clearance 70, and so that itslongitudinal axis is parallel to that of the rock drill.

4 At the front end of the motor unit, the skirt 56 of the closuresection sleeves with a slide fit over the cylindrical surface of theextension 35. The housing of the motor unit terminates at its rear endin an axially extending cylindrical tailpiece or mounting shaft 78 whichis supported by the bracket 77 (FIGS. 1, 2, 4). The bracket includes abase portion 79 rigidly secured by means of a group of bolts 81 to anexternal raised or bossed portion 82 of the rock drill housing. Acentral upright part 83 of the bracket has an axial hole 84 throughwhich the tailpiece slidably extends. Sleeving the tailpiece between afiat inner end face of the upright and an opposed fiat shoulder of thehousing of the motor unit is a thick shock absorbing ring or buffer 85.A second similar buffer ring 86 sleeves the tailpiece between opposedflat faces of the upright part of the bracket and a retaining washer S7.The washer sleeves over a reduced end 88 of the tailpiece and is held inabutment with a shoulder 89 of the tailpiece by means of a nut 91. Thenut holds the tailpiece and buffer rings in assembled relation to thebracket in such manner that there is no axial end play between thebuffer rings and the bracket or between the tailpiece and the bracket.The butter rings are made of suitable material which is resiliout andcompressible, which may be rubber, or a suitable plastic such as thatknown as polyurethane. It is understood that one or the other of thebuffer rings is compressible accordingly as axial pressure is applied tothe motor unit in one direction or the other. When this occurs, themotor unit has a corresponding sliding movement relative to theextension 35 at its forward end. So that the motor unit will not beundesirably limited in this axial movement, the bracket 77 is located onthe rock drill so that the extension 35 is not fully received into therecess 55 of the sleeve, as indicated by the clearance at 92; and aclearance, as indicated at 93, normally exists between the end of theextension and the back wall 47 of the sleeve 56. Shock forces impartedto the motor unit during the operation of the rock drill will cause themotor unit to move axially relative to its mountings and will beabsorbed by the buffer elements. The extent of this movement, however,is relatively slight, and the clearance 93 provided between theextension and the back wall of the sleeve is ample to allow for suchmovement.

Cylindrical keys 94 (FIGS. 2, S) are provided to prevent rotation of themotor unit relative to its mountings. Each key is press fitted into thewall of the extension 35 and has a rear portion extending with a slidefit into an axial bore 95 in the back wall 47 of the closure 48. Therear portions of the keys extend into the bores sufliciently to allowfor relative axial movement of the motor unit, as indicated by theclearance 96.

In summary of the nature of the apparatus: it is apparent that the rockdrill 10 and the independent rotation motor unit 11 may be operated,each independently of the other, and that the striking bar 17 isrotatable at the will of the operator independently of the operation ofthe rock drill or the reciprocating action of the piston. Further, thespeed of the motor in a positive direction is automatically controlledby the governor so as to be maintained at a desired rate during theoperation of the drill; but is not governed in a reverse direction.Further, by means of the mounting arrangement of the motor unit to therock drill, shocks imparted to the motor unit by pounding of the pistonagainst the striking bar are absorbed by the butter rings 85, 86 withoutconsequent damage to the motor unit. In this respect, the force of theshocks cause the motor unit to move back and forth along itslongitudinal axis. When the force of shock imparted to the motor unit isin a rearward direction, the tailpiece 78 slides axially rearwardrelative to the bracket 77 compressing the inner buffer ring as it doesso. In this rearward movement, the front end 48 of the motor unit slidesto a corresponding degree rearwardly relative to the extension 35, thekey elements 94 and the driving pinion shaft 32. When the force impartedto the motor unit is in the opposite direction, the tailpiece slidesforwardly relative to the bracket to compress the outer buffer ring 86between the washer 87 and the bracket portion -83; and in this movementof the motor unit, its forward end 48 slides forwardly a correspondingdegree relative to the extension 35, the key elements 94 and the drivingpinion shaft 32.

While the back and forth movement of the motor unit is substantiallyabsorbed or resisted by the buffer rings and is accordingly very slight,it is nevertheless such that if the front and rear ends of the motorunit were solidly mounted to the rock drill housing, the housing ofeither the motor unit or the rock drill would crack or otherwise becomedamaged. It has been found in the case of a solid mounting, relativemovement of a few thousandths of an inch of the motor unit relative tothe rock drill would be enough to cause failure of the mounting. Suchfailure would not occur here because of the manner in which the motorunit 11 is mounted to the rock drill.

It is further apparent that the motor unit 11 may be readily detachedfrom the housing of the rock drill for replacement or repairs byremoving the securing bolts 81 so as to detach the bracket 77 and thenby sliding the motor unit axially rearward until it is free of theextension 35.

What is claimed is:

1. In an independent rotation rock drill, including a rock drill memberhaving an elongated housing and a rotatable tool holder in the housing,and a motor unit arranged externally of the housing having itslongitudinal axis parallel to that of the rock drill and having adriving connection at a front end with the tool holder; means mountingthe motor unit to the housing for limited relative axial movementcomprising an axially slidable conncction of one end of the motor unitWith the housing, an axially slidable connection of the opposite end ofthe motor unit with the housing, and buffer means yieldably resistingthe motor unit in said movement.

2. In an independent rotation rock drill including a rock drill memberhaving an elongated housing and a rotatable tool holder in the housing,and a motor unit arranged externally of the housing having itslongitudinal axis parallel to that of the rock drill and having adriving connection at a front end with the tool holder; means mountingthe motor unit to the housing for limited relative axial movementcomprising a front slidable connection of the motor unit with thehousing, a rear slidable connection of the motor unit with the housing,and buffer means yieldably resisting the motor unit in said movement;wherein the front slidable connection includes a radial enlargement ofthe housing having a rearward axial extension, and a forwardly extendingsleeve of the motor unit in which the extension is slidably received.

3. In an independent rotation rock drill as in claim 2, wherein the rearslidable connection includes a bracket extending radially from thehousing of the rock drill having an axial hole, and a rearwardlyextending shaft of the motor unit slidably received in the hole.

4. In an independent rotation rock drill as in claim 3,

wherein the buffer means includes resilient compressible ring elementsmounted on the shaft to either side of the bracket and retainer meansholding the buffer means in abutment with the bracket.

5. In an independent rotation rock drill as in claim 4, wherein theretainer means includes a shoulder at one end of the shaft abuttableagainst the ring element at one side of the bracket, .a second abutmentslidable on the shaft abuttable against the ring element at the otherside of the bracket, and an adjustable member on the shaft adjustablealong the shaft relative to the second abutment to hold the resilientelements in abutting relation to the bracket.

6. In an independent rotation rock drill as in claim 3, wherein thebracket is detachably mounted to the rock drill housing.

7. In an independent rotation rock drill as in claim 2, wherein keyelements are provided for preventing rotation of the motor unit relativeto the enlargement of the rock drill housing.

8. In an independent rotation rock drill as in claim 7, wherein the keyelements are stationary with the enlargement and have axially extendingportions, and the motor unit has bores in which said extending portionsare slidably received.

9. In a rock drill having an elongated housing, a rotatable tool holderin the housing, a striking bar supported in the holder for rotationtherewith and having limited relative axial movement, and a pistonhammer reciprocable in the housing to pound the striking bar; a toolholder rotation means comprising a motor unit arranged externally of thehousing having its longitudinal axis parallel to that of the rock drill,and including a motor element housed in the motor unit having a frontdrive shaft; gearing drivingly connecting the drive shaft with the toolholder; and shock absorbing means mounting the motor unit to the housingfor absorbing the impact of shocks imparted to the motor unit by thepounding action of the piston hammer against the striking bar, wherein afirst port is provided for supplying operating air to the motor in apositive direction, a second port is provided for supplying operatingair to the motor in a reverse direction, valve means is provided foradmitting operating air selectively to either the first or the secondport, the motor element has a rear driving shaft, and a governorcontrolled valve is operatively connected to the rear driving shaft forcontrolling flow of operating air through the first port to the motor.

References Cited UNITED STATES PATENTS 2,246,910 6/1941 Amtsberg 173123,035,799 5/1962 Pierce 248-15 3,154,158 10/1964 Lincoln 1731053,232,176 2/1966 Henning et a1. 173l05 FRED C. MATTERN, JR., PrimalyExaminer. L. P. KESSLER, Assistant Examiner.

